Magnetic-inductive flow meter

Abstract

A magnetic-inductive flow meter includes: a measuring tube for guiding a flowable medium in a longitudinal direction; a measuring electrode arrangement for detecting a measurement voltage dependent on the flow velocity, induced in the medium, two measuring electrode groups opposite one another on the measuring tube; and a magnetic field generating device for generating a magnetic field which passes through the measuring tube and including at least two coil core groups, each having at least two coil cores, wherein a first and a second part of the measuring tube each include at least one coil core group, wherein two radii, which intersect the coil cores of a coil core group that lie externally in a cross-sectional plane of the measuring tube, enclose a centre angle β by which 80°≤β≤105°.

The invention claimed is: 
     
       1. A magnetic-inductive flow meter, the flow meter comprising:
 a measuring tube configured to convey a flowable medium in a longitudinal direction; 
 a measuring electrode arrangement adpated to detect a measurement voltage induced in the medium and dependent upon a flow velocity of the medium, wherein the measuring electrode arrangement includes two measuring electrode groups of measuring electrodes, which are fastened opposite each other on the measuring tube; and 
 a magnetic field generating device configured to generate a magnetic field that passes through the measuring tube, the magnetic field generating device including at least two coil core groups, each having at least two coil cores, 
 wherein a reference plane, which is spanned by a longitudinal axis of the measuring tube and a transverse axis of the measuring tube, which intersects measuring electrodes of the measuring electrode arrangement, divides the measuring tube into a first part and a second part, wherein the first and second parts of the measuring tube each include at least one coil core group, 
 wherein two radii, which intersect the coil cores of a coil core group that lie externally in a cross-sectional plane of the measuring tube, span a first center angle β, 
 wherein the first center angle is 30°≤β≤120°, 
 wherein, when the measuring electrode groups each comprise precisely one measuring electrode, the first center angle is 80°≤β≤105°, and 
 wherein, when the measuring electrode groups each comprise at least two measuring electrodes, the first center angle is 60°≤β≤80°. 
 
     
     
       2. The flow meter of  claim 1 , wherein two radii, each of which intersects a measuring electrode, which lies externally in a cross-sectional plane of the measuring tube, of a measuring electrode group, span a second center angle α, wherein 10°≤α≤60°. 
     
     
       3. The flow meter of  claim 2 , wherein the second center angle is 20°≤α≤40°. 
     
     
       4. The flow meter of  claim 1 , wherein each coil core group includes at least four coil cores, which are attached in a cross-sectional plane of the measuring tube,
 wherein the radii that each intersect the internally-situated coil cores of a coil core group span a third center angle γ such that the third center angle is 1°≤γ≤80°. 
 
     
     
       5. The flow meter of  claim 4 , wherein the third center angle is 10°≤γ≤40°. 
     
     
       6. The flow meter of  claim 1 , wherein each coil core group includes at least three coil cores, wherein one of the three coil cores is intersected by the transverse axis extending perpendicular to the reference plane. 
     
     
       7. The flow meter of  claim 1 , wherein a coil core extends through at least two coils, wherein a longitudinal axis of the coil core extends parallel to the longitudinal axis of the measuring tube. 
     
     
       8. The flow meter of  claim 1 , wherein all coils connected in series have an electrical resistance between 2 and 300Ω. 
     
     
       9. The flow meter of  claim 1 , wherein all coils connected in series have an electrical resistance between 150 and 260Ω. 
     
     
       10. The flow meter of  claim 1 , wherein the magnetic field generating device includes two pole shoes, wherein the pole shoes are fastened opposite each other,
 wherein the pole shoes each include at least two pole shoe bodies, and 
 wherein the pole shoe bodies comprise stacked sheets of sheet metal. 
 
     
     
       11. The flow meter of  claim 10 , wherein two adjacent pole shoe bodies are separated by a minimum distance in the longitudinal direction of the measuring tube, the minimum distance being less than 500 millimeters. 
     
     
       12. The flow meter of  claim 10 , further comprising a field return assembly attached as to abut an outer wall of the measuring tube, wherein the field return assembly comprises at least two field returns, wherein the coil cores connect the pole shoes to the field returns. 
     
     
       13. The flow meter of  claim 1 , wherein all measuring electrodes of one measuring electrode group of the two measuring electrode groups are electrically connected to each other. 
     
     
       14. The flow meter of  claim 1 , wherein the first and second parts of the measuring tube each have precisely two coil core groups, consisting of a first coil core group and a second coil core group arranged in the first part of the measuring tube,
 wherein the first coil core group is disposed in a first cross-sectional plane, and the second coil core group is disposed in a second cross-sectional plane, and 
 wherein the first and second cross-sectional planes are spaced apart in the longitudinal direction of the measuring tube. 
 
     
     
       15. The flow meter of  claim 1 , wherein the measuring electrode arrangement is arranged in a third cross-sectional plane,
 wherein the third cross-sectional plane is disposed between the first and second cross-sectional planes and defines a symmetry plane of the coil core groups and of the magnetic field generating device. 
 
     
     
       16. The flow meter of  claim 13 , wherein all measuring electrodes of one measuring electrode group of the two measuring electrode groups are electrically connected to each other by short-circuiting each other. 
     
     
       17. A magnetic-inductive flow meter, the flow meter comprising:
 a measuring tube configured to convey a flowable medium in a longitudinal direction; 
 a measuring electrode arrangement adpated to detect a measurement voltage induced in the medium and dependent upon a flow velocity of the medium, wherein the measuring electrode arrangement includes two measuring electrode groups of measuring electrodes, which are fastened opposite each other on the measuring tube; and 
 a magnetic field generating device configured to generate a magnetic field that passes through the measuring tube, the magnetic field generating device including at least two coil core groups, each having at least two coil cores, 
 wherein a reference plane, which is spanned by a longitudinal axis of the measuring tube and a transverse axis of the measuring tube, which intersects measuring electrodes of the measuring electrode arrangement, divides the measuring tube into a first part and a second part, wherein the first and second parts of the measuring tube each include at least one coil core group, 
 wherein two radii, which intersect the coil cores of a coil core group that lie externally in a cross-sectional plane of the measuring tube, span a first center angle β, 
 wherein the first center angle is 30°≤β≤120°, and 
 wherein two radii, each of which intersects a measuring electrode, which lies externally in a cross-sectional plane of the measuring tube, of a measuring electrode group, span a second center angle α, wherein the second center angle is 20°≤α40°. 
 
     
     
       18. The magnetic-inductive meter of  claim 17 , wherein, when the measuring electrode groups each comprise precisely one measuring electrode, the first center angle is 80°≤β≤105°, and
 wherein, when the measuring electrode groups each comprise at least two measuring electrodes, the first center angle is 60°≤β≤80°. 
 
     
     
       19. A magnetic-inductive flow meter, the flow meter comprising:
 a measuring tube configured to convey a flowable medium in a longitudinal direction; 
 a measuring electrode arrangement adpated to detect a measurement voltage induced in the medium and dependent upon a flow velocity of the medium, wherein the measuring electrode arrangement includes two measuring electrode groups of measuring electrodes, which are fastened opposite each other on the measuring tube; and 
 a magnetic field generating device configured to generate a magnetic field that passes through the measuring tube, the magnetic field generating device including at least two coil core groups, each having at least two coil cores, 
 wherein a reference plane, which is spanned by a longitudinal axis of the measuring tube and a transverse axis of the measuring tube, which intersects measuring electrodes of the measuring electrode arrangement, divides the measuring tube into a first part and a second part, wherein the first and second parts of the measuring tube each include at least one coil core group, 
 wherein two radii, which intersect the coil cores of a coil core group that lie externally in a cross-sectional plane of the measuring tube, span a first center angle β, wherein the first center angle is 30°≤β≤120°, 
 wherein the first and second parts of the measuring tube each have precisely two coil core groups, consisting of a first coil core group and a second coil core group arranged in the first part of the measuring tube, 
 wherein the first coil core group is disposed in a first cross-sectional plane, and the second coil core group is disposed in a second cross-sectional plane, and 
 wherein the first and second cross-sectional planes are spaced apart in the longitudinal direction of the measuring tube. 
 
     
     
       20. The magnetic-inductive flow meter of  claim 17 , wherein all measuring electrodes of one measuring electrode group of the two measuring electrode groups are electrically connected to each other by short-circuiting each other. 
     
     
       21. The magnetic-inductive flow meter of  claim 19 , wherein all measuring electrodes of one measuring electrode group of the two measuring electrode groups are electrically connected to each other by short-circuiting each other. 
     
     
       22. The magnetic-inductive flow meter of  claim 19 , wherein, when the measuring electrode groups each comprise precisely one measuring electrode, the first center angle is 80°≤β≤105°, and
 wherein, when the measuring electrode groups each comprise at least two measuring electrodes, the first center angle is 60°≤β≤80°. 
 
     
     
       23. The magnetic-inductive flow meter of  claim 19 , wherein two radii, each of which intersects a measuring electrode, which lies externally in a cross-sectional plane of the measuring tube, of a measuring electrode group, span a second center angle α, wherein 10°≤α≤60°. 
     
     
       24. The magnetic-inductive flow meter of  claim 19 , wherein each coil core group includes at least four coil cores, which are attached in a cross-sectional plane of the measuring tube,
 wherein the radii that each intersect the internally-situated coil cores of a coil core group span a third center angle γ such that the third center angle is 1°≤γ≤80°. 
 
     
     
       25. The magnetic-inductive flow meter of  claim 19 , wherein the measuring electrode arrangement is arranged in a third cross-sectional plane,
 wherein the third cross-sectional plane is disposed between the first and second cross-sectional planes and defines a symmetry plane of the coil core groups and of the magnetic field generating device.